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  <div class="section" id="mindspore-ops-roialign">
<h1>mindspore.ops.ROIAlign<a class="headerlink" href="#mindspore-ops-roialign" title="Permalink to this headline">¶</a></h1>
<dl class="class">
<dt id="mindspore.ops.ROIAlign">
<em class="property">class </em><code class="sig-prename descclassname">mindspore.ops.</code><code class="sig-name descname">ROIAlign</code><span class="sig-paren">(</span><em class="sig-param">pooled_height</em>, <em class="sig-param">pooled_width</em>, <em class="sig-param">spatial_scale</em>, <em class="sig-param">sample_num=2</em>, <em class="sig-param">roi_end_mode=1</em><span class="sig-paren">)</span><a class="reference internal" href="../../_modules/mindspore/ops/operations/nn_ops.html#ROIAlign"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#mindspore.ops.ROIAlign" title="Permalink to this definition">¶</a></dt>
<dd><p>Computes the Region of Interest (RoI) Align operator.</p>
<p>The operator computes the value of each sampling point by bilinear interpolation from the nearby grid points on the
feature map. No quantization is performed on any coordinates involved in the RoI, its bins, or the sampling
points. The details of (RoI) Align operator are described in <a class="reference external" href="https://arxiv.org/abs/1703.06870">Mask R-CNN</a>.</p>
<dl class="field-list simple">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><ul class="simple">
<li><p><strong>pooled_height</strong> (<a class="reference external" href="https://docs.python.org/library/functions.html#int" title="(in Python v3.8)"><em>int</em></a>) – The output features height.</p></li>
<li><p><strong>pooled_width</strong> (<a class="reference external" href="https://docs.python.org/library/functions.html#int" title="(in Python v3.8)"><em>int</em></a>) – The output features width.</p></li>
<li><p><strong>spatial_scale</strong> (<a class="reference external" href="https://docs.python.org/library/functions.html#float" title="(in Python v3.8)"><em>float</em></a>) – A scaling factor that maps the raw image coordinates to the input
feature map coordinates. Suppose the height of a RoI is <cite>ori_h</cite> in the raw image and <cite>fea_h</cite> in the
input feature map, the <cite>spatial_scale</cite> must be <cite>fea_h / ori_h</cite>.</p></li>
<li><p><strong>sample_num</strong> (<a class="reference external" href="https://docs.python.org/library/functions.html#int" title="(in Python v3.8)"><em>int</em></a>) – Number of sampling points. Default: 2.</p></li>
<li><p><strong>roi_end_mode</strong> (<a class="reference external" href="https://docs.python.org/library/functions.html#int" title="(in Python v3.8)"><em>int</em></a>) – Number must be 0 or 1. Default: 1.</p></li>
</ul>
</dd>
</dl>
<dl class="simple">
<dt>Inputs:</dt><dd><ul class="simple">
<li><p><strong>features</strong> (Tensor) - The input features, whose shape must be <span class="math notranslate nohighlight">\((N, C, H, W)\)</span>.</p></li>
<li><p><strong>rois</strong> (Tensor) - The shape is <span class="math notranslate nohighlight">\((rois\_n, 5)\)</span>. With data type of float16 or float32.
<cite>rois_n</cite> represents the number of RoI. The size of the second dimension must be <cite>5</cite> and the <cite>5</cite> colunms
are <span class="math notranslate nohighlight">\((image\_index, top\_left\_x, top\_left\_y, bottom\_right\_x, bottom\_right\_y)\)</span>.
<cite>image_index</cite> represents the index of image. <cite>top_left_x</cite> and <cite>top_left_y</cite> represent the <cite>x, y</cite>
coordinates of the top left corner of corresponding RoI, respectively. <cite>bottom_right_x</cite> and <cite>bottom_right_y</cite>
represent the <cite>x, y</cite> coordinates of the bottom right corner of corresponding RoI, respectively.</p></li>
</ul>
</dd>
<dt>Outputs:</dt><dd><p>Tensor, the shape is <span class="math notranslate nohighlight">\((rois\_n, C, pooled\_height, pooled\_width)\)</span>.</p>
</dd>
</dl>
<dl class="field-list simple">
<dt class="field-odd">Raises</dt>
<dd class="field-odd"><ul class="simple">
<li><p><a class="reference external" href="https://docs.python.org/library/exceptions.html#TypeError" title="(in Python v3.8)"><strong>TypeError</strong></a> – If <cite>pooled_height</cite>, <cite>pooled_width</cite>, <cite>sample_num</cite> or <cite>roi_end_mode</cite> is not an int.</p></li>
<li><p><a class="reference external" href="https://docs.python.org/library/exceptions.html#TypeError" title="(in Python v3.8)"><strong>TypeError</strong></a> – If <cite>spatial_scale</cite> is not a float.</p></li>
<li><p><a class="reference external" href="https://docs.python.org/library/exceptions.html#TypeError" title="(in Python v3.8)"><strong>TypeError</strong></a> – If <cite>features</cite> or <cite>rois</cite> is not a Tensor.</p></li>
</ul>
</dd>
</dl>
<dl class="simple">
<dt>Supported Platforms:</dt><dd><p><code class="docutils literal notranslate"><span class="pre">Ascend</span></code> <code class="docutils literal notranslate"><span class="pre">GPU</span></code> <code class="docutils literal notranslate"><span class="pre">CPU</span></code></p>
</dd>
</dl>
<p class="rubric">Examples</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">features</span> <span class="o">=</span> <span class="n">Tensor</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">array</span><span class="p">([[[[</span><span class="mf">1.</span><span class="p">,</span> <span class="mf">2.</span><span class="p">],</span> <span class="p">[</span><span class="mf">3.</span><span class="p">,</span> <span class="mf">4.</span><span class="p">]]]]),</span> <span class="n">mindspore</span><span class="o">.</span><span class="n">float32</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">rois</span> <span class="o">=</span> <span class="n">Tensor</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">array</span><span class="p">([[</span><span class="mi">0</span><span class="p">,</span> <span class="mf">0.2</span><span class="p">,</span> <span class="mf">0.3</span><span class="p">,</span> <span class="mf">0.2</span><span class="p">,</span> <span class="mf">0.3</span><span class="p">]]),</span> <span class="n">mindspore</span><span class="o">.</span><span class="n">float32</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">roi_align</span> <span class="o">=</span> <span class="n">ops</span><span class="o">.</span><span class="n">ROIAlign</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">output</span> <span class="o">=</span> <span class="n">roi_align</span><span class="p">(</span><span class="n">features</span><span class="p">,</span> <span class="n">rois</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">print</span><span class="p">(</span><span class="n">output</span><span class="p">)</span>
<span class="go">[[[[1.775 2.025]</span>
<span class="go">   [2.275 2.525]]]]</span>
</pre></div>
</div>
</dd></dl>

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